Jonas Sicking, Wed, 8 Feb 2012 18:47:56 -0800:
> The semantic meaning of the contents of a canvas is obviously
> different from the semantic meaning of the contents of a hidden
> element.
>
> However implementation-wise, the reason that they are special when
> exposed to AT is exactly the same.
>
> In firefox, the reason that @hidden elements are "stringified" when
> exposed through aria-describedby is because they don't have CSS boxes.
> This is also why we have problems currently when exposing the contents
> of a <canvas>. In both cases the accessibility code "fails" because it
> tries to use the CSS boxes which aren't there. Hence the fallback to
> stringify.
Just to clarify: Are you saying that whenever @aria-describedby points
to *non-hidden* content, then Firefox presents the fragment[s] that it
points to with full semantics?
In my previous tests, with VoiceOver, then I could not hear any
difference that depended on whether the element[s] to which
@aria-describedby pointed, were visible or not.
--
Leif H Silli